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Requirements change until they don't

https://buttondown.com/hillelwayne/archive/requirements-change-until-they-dont/

Published: April 24, 2025 11:00

Recently I got a question on formal methods1: how does it help to mathematically model systems when the system requirements are constantly changing? It doesn't make sense to spend a lot of time proving a design works, and then deliver the product and find…

The Halting Problem is a terrible example of NP-Harder

https://buttondown.com/hillelwayne/archive/the-halting-problem-is-a-terrible-example-of-np/

Published: April 16, 2025 17:39

Short one this time because I have a lot going on this week. In computation complexity, NP is the class of all decision problems (yes/no) where a potential proof (or "witness") for "yes" can be verified in polynomial time. For example, "does this set of…

Solving a "Layton Puzzle" with Prolog

https://buttondown.com/hillelwayne/archive/a48fce5b-8a05-4302-b620-9b26f057f145/

Published: April 8, 2025 18:34

I have a lot in the works for the this month's Logic for Programmers release. Among other things, I'm completely rewriting the chapter on Logic Programming Languages. I originally showcased the paradigm with puzzle solvers, like eight queens or…

[April Cools] Gaming Games for Non-Gamers

https://buttondown.com/hillelwayne/archive/april-cools-gaming-games-for-non-gamers/

Published: April 1, 2025 16:04

My April Cools is out! Gaming Games for Non-Gamers is a 3,000 word essay on video games worth playing if you've never enjoyed a video game before. Patreon notes here. (April Cools is a project where we write genuine content on non-normal topics. You can…

Betteridge's Law of Software Engineering Specialness

https://buttondown.com/hillelwayne/archive/betteridges-law-of-software-engineering/

Published: March 26, 2025 18:48

Logic for Programmers v0.8 now out! The new release has minor changes: new formatting for notes and a better introduction to predicates. I would have rolled it all into v0.9 next month but I like the monthly cadence. Get it here! Betteridge's Law of…

Verification-First Development

https://buttondown.com/hillelwayne/archive/verification-first-development/

Published: March 18, 2025 16:22

A while back I argued on the Blue Site1 that "test-first development" (TFD) was different than "test-driven development" (TDD). The former is "write tests before you write code", the latter is a paradigm, culture, and collection of norms that's based on…

New Blog Post: "A Perplexing Javascript Parsing Puzzle"

https://buttondown.com/hillelwayne/archive/new-blog-post-a-perplexing-javascript-parsing/

Published: March 12, 2025 14:49

I know I said we'd be back to normal newsletters this week and in fact had 80% of one already written. Then I unearthed something that was better left buried. Blog post here, Patreon notes here (Mostly an explanation of how I found this horror in the…

Five Kinds of Nondeterminism

https://buttondown.com/hillelwayne/archive/five-kinds-of-nondeterminism/

Published: February 19, 2025 19:37

No newsletter next week, I'm teaching a TLA+ workshop. Speaking of which: I spend a lot of time thinking about formal methods (and TLA+ specifically) because it's where the source of almost all my revenue. But I don't share most of the details because 90%…

Are Efficiency and Horizontal Scalability at odds?

https://buttondown.com/hillelwayne/archive/are-efficiency-and-horizontal-scalability-at-odds/

Published: February 12, 2025 18:26

Sorry for missing the newsletter last week! I started writing on Monday as normal, and by Wednesday the piece (about the hierarchy of controls ) was 2000 words and not close to done. So now it'll be a blog post sometime later this month. I also just…

What hard thing does your tech make easy?

https://buttondown.com/hillelwayne/archive/what-hard-thing-does-your-tech-make-easy/

Published: January 29, 2025 18:09

I occasionally receive emails asking me to look at the writer's new language/library/tool. Sometimes it's in an area I know well, like formal methods. Other times, I'm a complete stranger to the field. Regardless, I'm generally happy to check it out. When…